RN-AdS Nontopoligical Solitons in Broken Einstein-Maxwell-Higgs Theory

TL;DR

This paper investigates the existence, stability, and dynamics of nontopological solitons in Einstein-Maxwell-Higgs theory with broken U(1) symmetry, revealing complex behaviors including stability regions, fractal structures, and phase transitions in AdS spacetime.

Contribution

It introduces new numerical solutions of AdS nontopological solitons, analyzes their stability, and explores their evolution, including superextremal states and phase transition phenomena.

Findings

Stable and unstable regions depend on gravitational coupling parameter.

Long-term evolution shows fractal boundary structures.

Superextremal bubbles can induce phase transitions or form gravitating solutions.

Abstract

Results are presented from numerical simulations of the Einstein-Maxwell-Higgs equations with a broken U(1) symmetry. Coherent nontopological soliton solutions are shown to exist that separate an Anti-de Sitter (AdS) true vacuum interior from a Reissner-Nordstrom (RN) false vacuum exterior. The stability of these bubble solutions is tested by perturbing the charge of the coherent solution and evolving the time-dependent equations of motion. In the weak gravitational limit, the short-term stability depends on the sign of $(\omega/ Q) \, \partial_\omega Q$, similar to q-balls. The long-term end state of the perturbed solutions demonstrates a rich structure and is visualized using "phase diagrams." Regions of both stability and instability are shown to exist for $\kappa_g \lesssim 0.015$, while solutions with $\kappa_g \gtrsim 0.015$ were observed to be entirely unstable. Threshold solutions are shown to demonstrate time-scaling laws, and the space separating true and false vacuum end states is shown to be fractal in nature, similar to oscillons. Coherent states with superextremal charge-to-mass ratios are shown to exist and observed to collapse or expand, depending on the sign of the charge perturbation. Expanding superextremal bubbles induce a phase transition to the true AdS vacuum, while collapsing superextremal bubbles can form nonsingular strongly gravitating solutions with superextremal RN exteriors.